The present invention relates to a method of and an apparatus for controlling the work performed by an automatic work processing apparatus, and in particular, to a method of and an apparatus for controlling the of automatic work processing effected by use of robot.
With the development of automation of work processing, there has been broadly utilized a work processing in which an industrial robot is employed in various work processing fields. Welding is an example of such a work processing.
Incidentally, when perfroming the automatic welding, quality control becomes a problem in the weld processing. Various methods have already been proposed to solve this problem.
For example, the Japanese Patent Publication No. JP-B-52-10773 proposes a method wherein the position of a welding torch is controlled to weave to the right and to the left with respect to a welding path such that the same welding states appear at the right and left ends of the weaving motion, thereby attaining a satisfactory quality of the welding work. According to this method, a shift of the position of a work or workpiece as an object of the welding is allowed to some extent so as to keep the desired welding quality; however, considerations have not been given to a case where a gap exists between workpieces and to a case where the value of the welding current varies due to some external disturbance.
In addition, U.S. Pat. No. 4567347 discloses a method in which a form of an opening end of a workpiece is detected by use of a laser light so as to control a welding torch. According to this method, a shift of a position of the workpiece and a change of a gap can be coped with by modifying the processing to be achieved after the detection of the form of the opening end, which enables a satisfactory welding quality to be attained.
Considerations have not been given to cases where the final bead appearance, namely, the weld result deteriorates due to a change in the thickness of a plate associated with a fluctuation in the precision of parts or because of a variation in the welding current and/or voltage associated with an external disturbance.
The welding phenomenon is quite complex and there exist many parameters that effect the welding quality such as welding speed, a welding attitude or position, a welding current, a welding voltage, a wire supply speed, a welding power characteristic, a shield gas, a wire radius, a wire kind, a dynamic characteristic of an automatic welding machine, a plate thickness of a workpiece, a material quality of a workpiece, a shape of a joint, and a precision of the work processing apparatus.